The present invention relates to an improved jamming cleat for releasably holding ropes, cords, cables and similar elongate articles.
Jamming cleats for holding ropes are well known and there is described in U.S. Pat. No. 3,574,900 of Reginald J. Emery a jamming cleat having a groove opening out of one side of the cleat and extending over the whole length of the cleat, the groove having opposed internal faces which converge towards the bottom of the groove and ridges on each face, the ridges on both faces being inclined to the base of the groove upwardly from one end of the groove. The internal faces of this known cleat are uniformly spaced along the length of the groove and in use a rope is inserted laterally into the mouth of the groove and the rope is pulled through the cleat so that the ridges draw the rope downwardly towards the bottom of the groove where it is jammed tightly in the cleat.
This type of cleat has proved satisfactory in many applications but I have found that it has limitations both in the range of rope diameters which a cleat of any given size will grip effectively and in the pulling force which the cleat can withstand without failure. When this known type of cleat is loaded the front ridges normally provide most of the grip on the rope. As the loading increases the rope tends to stretch and each tooth takes progressively less load, causing the front end of the rope to be pulled downwardly into the groove further than the rear end of the rope. As a result of these factors, the load applied to the cleat is always taken mainly by the first one or two ridges. This limits the maximum loading of a cleat of a given size and the range of rope diameters which any given cleat can grip effectively. It also creates a localised strain on the rope so that the maximum loading that a given rope can withstand is much less than it would be if the loading was spread over a greater length of the rope.
I have now found that, if the cleat is so designed that the crests of the ridges diverge lengthwise of the groove from the rear end of the groove towards the front end of the groove the rope will be gripped more uniformly along the length of the groove by a greater number of ridges thereby substantially increasing the holding power of the cleat and the range of diameters of rope which a given size of cleat will grip effectively and also spreading the load on the rope itself.